Internal micrometer caliper



July 29, 19u52 H, MEYER 2,604,703

- INTERNAL MICROMETER CALIPER I Filed Feb. 25, 1948 39 fr/////. Z 4s 'l fhg-i 40 24 the following parts:

Patented July 29, 1952 INTERNAL MICROMETER ACALIPER Hans Meyer, Renens, Switzerland, assigner, by

mesne assignments, to Brown & Sharpe Manufacturing Company, Providence, It. I., a corporation of Rhode Island Application February 25, 1948, serial No. 10.764

, In Switzerland |0ctobcr'11, 1943 1` My invention relates to improvements in internal' micrometer calipers, in which the measuring spindle is provided with a threaded cone head for displacing a series of spring-loaded contact elements at right angles thereto; and the main object of my improvement is to provide an instrument of simple construction for measuring the width of bores, apertures, and the distance between plates and the like.

I attain this and related objects bythe instrument shown, in various adaptations, inthe accompanying drawings, in which- Fig. 1 is a fragmentary longitudinal section through a preferred form of invention, y

Fig. 2 is a fragmentary elevation of the same,

Fig. 3 is a cross-section on the line AL-A of Fig. 1,

Fig. 4 is a view, partly in section, of a second form of ratchet stop for the measuring spindle, Fig.. 5 is a cross-section, taken on the axis of the instrument, lof any auxiliary extension-contact structure plugged over the instrument head, and f Figs. 6 and 7 are fragmentary longitudinal sections of the instrument head provided withrsets of contact elements disposed in line. f Y

The instrument according to Fig. l comprises The measuring spindle 2 is threaded in the guide sleeve I vby means of the micrometer threads 4, and is provided at its head with a threaded cone end 3. The tapered outer lend 5 of the said measuring spindle 2 projects from the said sleeve I and is rigidly secured to the thimble 1 by means of the screw 8 and the washer 9. The thimble 1 serves as drive element for the spindle 2 and its cone head 3, and

is provided with a circular scale of graduations 6, In the form of invention shown there arethree contact buttons III circumferentially disposed at equal distances in bores I2 of a retainer sleeve II, in which they are radially displaceable. The

sleeve II is telescoped over and secured to the guide sleeve I, and it is closed at its inner end by a domed cap IIa which is secured to the sleeve II by screws IIb. The base portions of the contact buttons I are tapered and of ccncave shape and provided with threads I 0b for engaging the threaded cone 3, while their head portions IIla are cylindrical and of convex shape concentric with the sleeve II, Three wing springs I3 (Fig. 3), secured to screws I4 and housed in slots I of the contact buttons I0 yieldingly urge the latter lightly inwardly against the positive spreading action of the ,propelling `c. claims. (ci. 33 178) 2 cone 3. The springs I3, therefore, also'guara'ntee a proper engagement of the corresponding threads on the contact buttons Ib and the cone 3.

In order to secure the sleeve II on the guide sleeve I against any rotative displacement relative tol the latter, the sleeve II is provided with a groove I6 which is engaged by a key I1 disposed on the sleeve I. The sleeve II, furthermore, is secured longitudinally by a ring I8 having a reduced diameter inner end threaded into internal threads I9 at the outer end of the sleeve I I to seat against a radial shoulder of the guide sleeve I. The ring I8l is secured against axial displacement in the opposite direction by the radial shoulder 2I of a hub 2Ia which is anchored to the sleeve I by a set screw 2 I f.

- The thimble 'I, together with the measuring spindle 2, is rotated by means of the ratchet stop secured to its outer end. The ratchet stop serves to maintain an approximately equal measuring pressure on the contact buttons IIl, and vcomprises the shouldered shank 8a of the screw 8, a helical spring 23 disposed on the said shank, and a turning knob 22 which is provided with an axial slot for receiving the end 23a of the `said spring 23. The'spring 23, due to its own friction, grips' the shanka; f When turning the knob 22 clockwise-as seen from the outer or turning knob end of the instrumentthe spring 23 slackens on account of the torque to be overcome in the measuring operation, and thecontact buttons I0 are spread apart'. When the said torque has attained a certain value, corresponding -to the measuring pressure desired, the spring 23 starts to slip on the screw shank 8a, and becomes disengaged from the thimble 1. At this moment, therefore, the measuring spindle 2 comes to rest, and the friction in the threads Ib and 4 maintains a constant measuring pressure on the walls of the bore to be measured. Upon turning the knob 22 counterclockwise, the frictional pressure of the spring 23 uponA the shank 801, is increased, ,and the thimble 'I becomes coupled to the knob 22.`

In order to be able to read fractions of an interval of the circular scale of graduations. 6 with reference to the marking line 2Ib, the hub 2Ia is provided with a vernier scale 2Ic. The full revolutions of the thimble 1 upon the hub 2 Ia and, therefore, also on the sleeve I, are read from the lineal divisions 2Id.r The hub 2Ia is sleeve I to form a housing for the spindle 2. the threaded cone 3 and the contact buttons or feeler members I0, and the elements lli-2 Ia, serve only for mounting and demounting purposes. The connection between the sleeves II and I also could be effected by means of latches or pawls. Again,` the sleeve Il could be made an integral part of sleeve I, or the latter could be adapted as a retainer sleeve. o

The instrument shown in Figs. 1 and 2 could be constructed in part to differ from the'form shown. without, however, departing from the scope of the present invention.

Among these structural variations, I refer t f the following:

The cylindrical surface of the head Iller, of the contact buttons I0 assures alineal contact between the latter and the wall of the bore to be measured, and the said buttons thus arek aligned accurately at right angles to the said wall. The surface of the head Illa also, of course, could be shaped differently; they, e. g., could1bespher ieally adapted, or given' a shape whichpermits of measuring inside threads and the like. To

`'prevent too quick a `wear of the surface Illa, .the -latter can be chromium-plated orl given a coat of some hard metal.

Thespiral threads on the 'cone 3,; as vto form,

. pitch,v and taper, may be adapted to the purpose of the measuring instrument at -hand.'

Suitably, a thread is chosen, the one-flank of which runs parallel to the cone axis, while the other extends at right angles thereto.

` In-view of the simple design of -thestructure, o the instrument suitably isequippedwithonly or more threaded cones provided-on-'the measfuring spindle; in which vease' the contact ele- .'.ments either may be sodisposed that'eachcone `actuates a separate set of contact elements, or

`so thateach of the latter engages each cone. In

Figs. 6 and 'lltwo of these possible dispositions *are shown' ,diagramln'atically;v In ,the example ".shown in Fig. 6,7each of the cones 24 and 25e@- Voperates witha-set 26 and 27 of contact'elemnts;

the two `sets 'being independent of neachy other. In the example shown in Fig.f7,:thereisonly one setof contact elements 28 whichseach-,en-

gagefboth cones'24:- and 25 by vtheir correspondy ing legs 29 and 30.

The other elements of the instrument may `^be analogous to those shown in Figs.l land 2. f

In the -form `shownin Fig; ,1; the threaded v cone 3 is 'made integral with the measuring spindle 2; `itphoweverl also may :belooselyoon.

nected tothe latter, in which case 'measures must1 be taken to prevent a rotation of `the `axially byv the threads l 4A of y. the latter. "I'he :threadsl of thecone=3 have thesame pitch as ithethreads 4.which effectthe displacement of thezspindle 2,2 and cone 3,-therefore, isinfthe proper position Vin each measuring-setting;

In place 'of theiratchet stopdeviceshown in Figs. 1 and'Z, for actuatingthei'thimblev '1,.1 an- 'Uother form: of ratchet stop-aasfshowndn'ilig.

rigidly connected to`= the' thimbla byfthe screw 3l. A ring-pawlf33, r'sliding upon thewideshank 'f 3-Ia of the screw 3l, is 'pushed against* the `ratchet wheel 32 by the'helical spring 35. When turning the knob 31, the ratchetwheel 33l is turned also, since the ylatter is provided. with a 4 keyway 38 which is engaged by a pin 34 rigidly secured to the said knob 3l. The teeth 36 are adapted so as to become disengaged, upon turning the knob 31 clockwise, as soon as the preselected maximum torque has been attained; and to effect a fast. coupling-between thimble 1 and knob 31 upon turning the latter counterclockwise.

In order to extend the measuring range of the instrument, the possibility of increasing the di- `ameterrange of the contact buttons I Il has been provided for.v Fig. shows such an example of execution, in which an additional contact sleeve,

-' containingauxiliary contact buttons, is plugged over the base yretainer sleeve I I.

In this last form, the superimposed sleeve 39 .comprises contact button extensions 40 corretact buttons I0 in the retainer sleeve Il.

Y thefretainen 42. A pin 44, secured to the sleeve 39, engages the slotf43 in the sleeve II and prevents thus a rotation of the sleeve 39. vThe latter is secured vagainst axial displacement on the ,sleeve II- by the kcap nut 45 screwed'onto -the threads' 46 in the headof the sleeve fII..V Obviouslythere are` also' other ways of fastening sleeve 39 tosleeve Il possible. e

The instrument shown and described is -used as follows:

The retainer ysleevel II isv introduced into the bore to be measured with the cone 3 inl the posinon shown in Fig, 1. 4.By turning. the knob 22,

the thimble 'I and -thus also the cone 3- is screwed forward until the spreading contact -buttons I0 contact the wall of the bore under a certainpredetermined pressure, i. e. the measuring pressure set bythe: friction of the spring 23 on the 4o.

shank Saffof l. After this pressure has been surpassed, the friction coupling ofthe 'ratchet lmayV bewithdrawn from' the bore.

l stop becomes disengaged from the spindle'Z and the cone 3. The bore diameter now maybe read Voff the reference mark 2lb onrthe scales 2Id and 6 of the. hub gld. (Fig. 2);. The thimble 1 then is screwed :backward of., the hub 2Ia,y by means' of the knob 22,'v uponwhichvthe contact buttons are withdrawn intothe -sleeve II under the' actionof .the springs I3, and the sleeve Il '."I'am-aware that priorto my'inVention-inside 'l micrometer` caiipers'have been designed in which one orme-re contact'elements were disposed'radially of .landuhadinner conical ysurfaces seated upon a cone which was displaced' axially'by a driving 4elernent,'whereby:the contact elements were displacedat right 'ahglestoithe axial vdis- Y"Patent is:

placement of the cone. I; therefore, do not claim f sucha` combinatioiizbrcadly; but

What I 'claim' anddesir'e to secure, by Letters *'l. VAn"inte'rnal micrometer 'caliper ,"comp'risi'ng lone contact element 'in positive engagement with '.:the said threaded cone'and radially 'dsplaceable --thereby' relative'to the axis of said spindle.

2. An `internal -inicrometer caliperk as defined in: claim' l,A 'comprising/a driving element 'secured .to said measuring spindle and having fixed there- -t =a graduated thimble, fand v,tiguimrsleeve in "which said.'measuringlspindleis threaded lfor axial displacement'oh rotationof said spindle -wwith Vrespectfto said guide. sleeve,` thefpitch.' ofthe threaded 'connection of saidA spindle,and=said guide sleeve being identical with the pitch ofthe threads of said cone.

3. An internal micrometer caliper, comprising a measuring spindle, a ratchet stop-and-thimble drive therefor, a hub enclosing a threaded sleeve for guiding the said spindle, two threaded cones disposed in line with and fastly secured to one end of the said spindle, and a plurality of springloaded contact elements in positive engagement with the said threaded cones and displaceable at right angles thereto.

4. An internal micrometer caliper as dened in claim 3, wherein said plurality of contact elements comprises two sets of contact elements of which each set co-operates with a different one of the said threaded cones.

5. An internal micrometer caliper as definedV in claim 3, wherein said plurality of contact elements comprises a set of contact elements each co-cperating with both said threaded cones.

6. An internal micrometer caliper comprising a guide sleeve having an internally threaded portion, a measuring spindle supported by said guide sleeve for rotation about its axis and for longitudinal displacement, said spindle having threads engaged with said internally threaded portion of said guide sleeve, a threaded cone carried by said spindle, the pitches of the threads of said cone and of said spindle being equal, a plurality of feeler elements spaced circumierentially around said threaded cone and having inner threaded ends seated upon said cone, spring means yieldingly retaining said feeler elements in engagement with said threaded cone, and scale means including a longitudinal scale corresponding to unit rotations of said measuring spindle and a 6 circumferential scale on a thimble secured to said measuring spindle. y 7. In an internal micrometer caliper, the invention as recited in claim 6, wherein one flank of the thread of said cone is parallel to the axis of said measuring spindle and the other iiank is "Y normal thereto.

8. In an internal micrometer caliper, the invention as recited in claim 6, wherein a retainer sleeve is connected to said guide sleeve and provided with circumferentially spaced apertures in which said feeler elements are guided for movement radially of the axis of said spindle and threaded cone.

HANS MEYER.

REFERENCES CITED v'.he following references are of record in the file of this patent:

UNITED STATES PATENTS 

